【Chemical name】：But-3-en-3-olide    4-methylideneoxetan-2-one

【CAS RN】： 674-82-8            【EINECS RN】：211-617-1 

【Molecular formula】：C4H4O2        【Molecular weight】：84.07

【Main usage】：It is lively as raw materials of diacetyl , also used for dye, pigment, pharmaceutical intermediate and herbicide.